Industrial Research 



353 



of the relatively large number of measiirin<i instruments 

 that have been developed in this field, biojjhysic'al in- 

 vestigations in this region have been unusually profuse 

 and of unusual significance. 



Extensive studies have been made of the bactericidal 

 action of light, and the resiUts have been put to good 

 practical use in industry and in medicine. Similarly, 

 studies of the ctrccts of light on the more important of 

 the useful micro-organisms, notably on the butyric and 

 lactic acid bacteria and the fungi involved in the making 

 of cheese have had important repercussions on proce- 

 dures in the dairy industry. Many more studies of this 

 kind are badly needed, in view of the ever-increasing 

 range of bacterial and fungus forms that are becoming 

 of industrial significance. 



The careful study of the effect of visible light of dif- 

 ferent wave lengths on photosynthesis has been of the 

 very highest importance to agriculture. The investiga- 

 tion of the mechanism of photosynthesis, wliich is only 

 in its infancy, has been prinaarily a biochemical matter, 

 but the biophysicist has contributed the methodology 

 for the direct investigation of plant growth in light of 

 differing quality, and in differing total illuminations. 

 The demonstration of the striking differences in the 

 requirements of various crop plants has alone more than 

 justified this work. The residts have already led to 

 marked modifications in commercial greenhouse tech- 

 nique, and may go much further. The dairy and 

 poultry industries have likewise been much influenced 

 by studies of the effects of quantity and quality of 

 illumination upon the rate and total production of milk, 

 egg, and meat products. Modifications of the fii'st and 

 second have been especially industrially important. 



Biophysical studies in the region of the visible spec- 

 trum have been of consequence in quite another field, 

 important to industrial medicine and to industry as a 

 whole — the field of opthalmology, and the study of the 

 effect of intensity and quality of light on the human eye. 

 Studies in the relative sensitivity of the human retina 

 to different portions of the visible spectrum have en- 

 abled progressive industrialists to provide the quality of 

 shop and office illumination to promote the highest effi- 

 ciency of work and the greatest happiness to workers. 

 Physical studies in the production of suitable fluorescent 

 light sources have aided this development enormously 

 in the last several years. On the other hand, biophys- 

 ical studies in the reaction of the himian eye to various 

 qualities and quantities of light have resulted in the 

 development of methods of opthalmological diagnosis 

 and treatment of very high value to industrial medicine. 



When we enter the ultraviolet region, we first come to 

 deal with rndiations of sufficient quantum energies to 

 produce fairly extensive ionization in the biological 

 materials upon which they impinge, resulting in the pro- 

 duction of numerous effects which yield much material 



of interest for the investigation of the biophysicist. The 

 chemical changes which ultraviolet radiation may bring 

 about have enabled biophysicists to be of great indus- 

 trial service in devising means for the artificial irradia- 

 tion of processed foods and of suitable sterols, with con- 

 sequent vitamin production. The process has come to 

 have fully as much industrial advertising as scientific 

 value, and is in some danger of having its merits over- 

 stressed thereby, but there is no denying its wide appli- 

 cability and industrial and medical import. Of similar 

 importance have been biophysical studies of the effects 

 of ultraviolet illumination on the human skin and eye, 

 the production of erythema, and the synthesis of vita- 

 mins under these conditions of extreme significance to 

 medicine and to industry. 



The property of ultraviolet light of inducing fluores- 

 cence in various substances has led to important bio- 

 physical applications, both industrially and medically. 

 In many cases living organisms fluoresce differently 

 from their nonliving counterparts, and the property may 

 be made of importance in a large-scale distinction be- 

 tween the two. Medically this has proved of impor- 

 tance in the examination of teeth. In industry, it can 

 be put to analogous use. 



Biophysicists have made extensive industrial use of 

 the bactericidal properties of ultraviolet light. As a 

 disinfecting agent, ultraviolet light is especially suitable 

 in treating surfaces where no part is in shadow, because 

 of the limited penetrating powers of light of this wave 

 length. Special sterilizing lamps have been developed 

 by industry which have proved especially useful in the 

 disinfection of mUk and water supplies, where it has 

 been possible to flow the liquid past the light source in 

 very thin sheets. The lamp has achieved a more limited 

 application in the disinfection of refrigerators, and to a 

 certain extent, in the treatment of fruits, where it has 

 been desirable to produce sufficiently intense illumina- 

 tion to eliminate deep shadows. Lamps designed for 

 the irradiation of patients or animals suffering from 

 rickets can, by the use of suitable soiu-ces and filters, 

 be converted into sterilizing agencies, thus making the 

 tool one of unusual flexibility. 



It has been claimed that the use of ultraviolet light 

 may be efficacious in the treatment of certain types of 

 surface cancers. This potentially important industrial- 

 medical application must await further biophysical 

 study. In photography, however, ultraviolet light 

 sources are of the greatest value to the biophysical in- 

 vestigator, both because their fluorescence-inducing 

 properties make them of great value in the fluorescence 

 microscope, and because their high absorption in cel- 

 lular nuclear material and this high resolving power 

 make them of gi-eat use in cell photomicrography. The 

 fluorescence microscope finds very considerable indus- 

 trial application in the analysis of materials which are 



